hw/timer/bcm2835: Rename variable holding CTRL_STATUS register

hw/timer/bcm2835: Rename variable holding CTRL_STATUS register

The variable holding the CTRL_STATUS register is misnamed
'status'. Rename it 'ctrl_status' to make it more obvious
this register is also used to control the peripheral.

Reviewed-by: Luc Michel <luc.michel@greensocs.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20201010203709.3116542-3-f4bug@amsat.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>